Currently used chemical laser devices operate with a plenum chamber which is provided with gases which are heated by combustion or other means to produce atomic or free radical species and are structurally arranged as illustrated in prior art FIGS. 1, 2 and 3. For example, F.sub.2 is heated to give F-atoms. Diluent gases such as He or N.sub.2 are also added and heated in the plenum. Following the plenum, the gases are expanded through a supersonic nozzle to a high velocity and low pressure. The gases exit the nozzle to a cavity and form a free jet. H.sub.2 or D.sub.2 gases are injected into the cavity and mixed with the expanded F-containing free jet. The reaction with F-atoms initiates the chemical pumping mechanism which yields vibrationally excited HF or DF. Mirrors are placed in the cavity and lasing results from the vibrationally excited HF or DF. The gases are then pumped to a pressure such that atmospheric exhaust is possible. As illustrated in FIG. 2, aerodynamic considerations dictate the illustrated dimensions L, T, and W. It has been found both experimentally and theoretically that aerodynamic restrictions leading to the L, T, and W dimensions, together with the high plenum temperatures required for prior art lasing operation give rise to severe viscous effects in the supersonic nozzle defined by the dimensions L, T, and W. With He as a diluent and plenum temperatures in excess of 1000.degree. K., it has been found that the flow exiting from the nozzles of working devices is totally viscous, i.e., the influence of the wall drag is distributed throughout the jet flow. The detrimental aspects of the viscous flow are a loss in total pressure, a decrease in the gas exit velocity and an increase in gas exit temperature, i.e., a decrease in Mach number. The attendant decrease in initial Mach number of the reacting streams dictates large quantities of diluent gases be included to prevent thermal choking of the flow in the presence of heat addition. Loss of total pressure and increased diluent ratios give rise to increased pumping requirements. Either a decrease in gas velocity or an increase in gas exit temperature lead to a reduction in the length of the gain supporting laser region with consequent degradation of laser beam coherence and increased mirror loading.
Therefore, it can be clearly seen that there is a need for better nozzle arrangements for introducing the free radical species with the secondary gases of D.sub.2 or H.sub.2.
Accordingly, it is an object of this invention to provide a chemical laser with a nozzle arrangement which operates supersonically at higher mass and laser efficiencies than that achievable in the more conventional prior art arrangements.
Another object of this invention is to provide a chemical laser nozzle arrangement that has efficiencies in excess of those achieved by conventional approaches in the art.
Still another object of this invention is to provide a supersonic nozzle with hypersonic wedges at the exit end of the diverging portions of the nozzle and with injection means for injecting secondary gases such as D.sub.2 or H.sub.2 into the jet stream of the primary gas or gases.
Other objects and advantages of this invention will be obvious to those skilled in this art.